Sewing machine

ABSTRACT

Disclosure relates to sewing machine capable of preventing thread cutting or deterioration caused by interference between leading end of needle and upper thread, that includes: head frame; needle bar supported on head frame to be movable up and down; needle having needle hole that penetrates in transverse direction with respect to axial line and has upper thread inserted thereinto and be coupled to lower end of needle bar to move up and down between lowered stitching position and lifted needle position; and presser foot unit having pressing part that is provided with needle guide hole through which needle passes and moves up and down between downward pressing height position where pressing part presses sewing material and lifting release height position where pressing part is lifted and spaced apart from sewing material and pressing foot arm that supports pressing part.

TECHNICAL FIELD [1] The disclosure relates to a sewing machine. BACKGROUND ART

In a sewing machine, a needle moves up and down vertically to form a stitch on a sewing material horizontally arranged. To this end, the needle is provided with a needle hole penetrating in a transverse direction, and an upper thread is lowered from the top, passes through the needle hole, and then extends downward. In the existing sewing machine, the sewing material mainly move linearly in one direction, but in a sewing machine, such as an embroidery machine, which forms various patterns, the sewing material moves in forward and backward and left and right directions within a horizontal plane with respect to an axial line of the needle.

Due to such a horizontal movement of the sewing material in forward and backward and left and right directions, an interference phenomenon that the upper thread under the needle hole may brush a leading end of the needle may frequently occur. In particular, since a relatively large tension is applied to the upper thread when the needle is lifted, the interference with the leading end of the needle may cause serious damage to the upper thread, which may be a serious cause of the occurrence of thread cutting and the reduction in efficiency accordingly, or a factor of deterioration in stitch quality.

DISCLOSURE Technical Problem

Accordingly, an object of the disclosure is to provide a sewing machine capable of effectively preventing an occurrence of thread cutting or deterioration in quality caused by interference between a leading end of a needle and an upper thread.

Technical Solution

According to an aspect of the present disclosure, a sewing machine includes: a head frame; a needle bar configured to be supported on the head frame to be movable up and down; a needle configured to have a needle hole that penetrates in a transverse direction with respect to an axial line and has an upper thread inserted thereinto and be coupled to a lower end of the needle bar to move up and down between a lowered stitching position and a lifted needle position; and a presser foot unit configured to have a pressing part that is provided with a needle guide hole through which the needle passes, and moves up and down between a downward pressing height position where the pressing part presses a sewing material and a lifting release height position where the pressing part is lifted and spaced apart from the sewing material and a pressing foot arm that supports the pressing part, and dispose the pressing part at a normal horizontal position so that the needle passes through the needle guide hole when the pressing part is at the downward pressing height position, and horizontally move the pressing part from the normal horizontal position to an excursion horizontal position spaced by a predetermined horizontal excursion amount so that the upper thread passing through the needle hole does not interfere with a leading end of the needle when the pressing part is at the lifting release height position.

The presser foot arm may support the pressing part to enable the pressing part to perform an excursion movement and a return movement between the normal horizontal position and the excursion horizontal position, and the sewing machine may further include an excursion driver configured to apply an excursion acting force to the presser foot arm to cause the pressing arm to perform at least one of the excursion movement and the return movement.

The excursion driver may include an excursion profile part whose lateral protrusion height gradually changes along an elevating direction on the presser foot arm, and a contact action member that contacts the excursion profile part to apply the excursion acting force, so the contact action member applies a contact acting force to the excursion profile part, thereby changing the pressing part between the normal horizontal position and the excursion horizontal position.

The contact action member may have a rolling contact part.

The excursion driver may include an excursion cam roller that rotates in contact with a side surface of the presser foot arm and applies the excursion acting force to the presser foot arm, and a roller driver that rotatably drives the excursion cam roller by interlocking with an elevating movement of the presser foot arm.

The sewing machine may further include: a reaction elastic member configured to apply an elastic force to the presser foot arm in a direction opposite to the excursion acting force, thereby stably moving the pressing part between the normal horizontal position and the excursion horizontal position.

Advantageous Effects

According to the disclosure, the sewing machine can effectively prevent the thread cutting or the deterioration in quality caused by the interference between the leading end of the needle and the upper thread.

DESCRIPTION OF DRAWINGS

FIG. 1 is a main partial cross-sectional view of a sewing machine according to the most preferred embodiment of the disclosure.

FIG. 2 is a cross-sectional view illustrating when a needle and a presser foot unit are in a lifted position.

FIG. 3 is a diagram for describing a state in which a downward extending portion of an upper thread excurses and is spaced apart from the needle.

FIGS. 4 and 5 each are diagrams illustrating a state in which a pressing part is at a normal horizontal position and an excursion horizontal position in a second embodiment.

FIGS. 6 and 7 each are diagrams illustrating a state in which a pressing part is at a normal horizontal position and an excursion horizontal position in a third embodiment.

FIG. 8 is a diagram illustrating a sewing machine according to a fourth embodiment.

MODE FOR DISCLOSURE

FIG. 1 is a main partial cross-sectional view of a sewing machine according to the most preferred embodiment (first embodiment) of the disclosure. The sewing machine according to the first embodiment includes a head frame 10, a needle bar 100 that can be elevated along a vertical axial line, a presser foot unit 200, an excursion driver, and a reaction elastic member 500.

The head frame 10 refers to a structure supporting a moving structure such as the needle bar 100 and the presser foot unit 200.

The needle bar 100 is supported on the head frame 10 to be movable up and down, and a lower end thereof is detachably coupled to a needle 110. The needle 110 has a needle hole 111 formed by penetrating in a transverse direction with respect to an axial line in an area of a leading end 112 and a needle tip 113 provided at an end thereof, and is lowered according to the elevating movement of the needle bar 100, passes through a sewing material 30, and moves up and down between a stitching position forming a stitch and a lifted needle position lifted from the stitching position.

The presser foot unit 200 includes a pressing part 220 having a needle guide hole 221 through which the needle can pass and a presser foot arm 210.

The pressing part 220 moves up and down between a downward pressing height position where the sewing material 30 is pressed to a lower surface by the lowering of the pressing part 220, and a lifting release height position where the pressing part 220 is lifted and spaced apart from the sewing material 30 by the lifting of the pressing part 220. The needle guide hole 221 is aligned to match the axial line of the needle 110 so that the needle 110 and the upper thread 20 can pass together while the pressing part 220 presses the sewing material 30.

As illustrated, an upper end of the presser foot arm 210 is bent so that the presser foot arm 210 is connected to the needle bar 100, and a middle area of thereof is bent so that the presser foot arm 210 crosses the needle bar 100, in which the middle area is provided with a cross passing hole 211 through which the needle bar 100 passes. The cross passing hole 211 allows the needle bar 100 to pass therethrough with a sufficient margin so that the presser foot arm 210 can excurse (or displace or deviate) and fluctuate laterally within a predetermined range with respect to the needle bar 100. Therefore, when the presser foot arm 210 excurses and fluctuates, the pressing part 220 connected to the lower end of the presser foot arm 210 can excurse and move to a certain extent in a horizontal direction with respect to the axial line of the needle bar 100. Through such an excursion movement, the presser foot arm 210 moves the pressing part 220 to a normal horizontal position while supporting the pressing part 220 so that the needle 110 can pass through the needle guide hole 221 when the pressing part 220 is at the downward pressing height position, and moves the pressing part 220 from the normal horizontal position to an excursion horizontal position spaced apart by a predetermined horizontal excursion amount (dS) in the horizontal direction when the pressing part 220 is at a lifting release height position. While the pressing part 220 moves to the excursion horizontal position, an inner side surface of the needle guide hole 221 is in contact with the downward extending portion 21 of the upper thread 20 to separate the downward extending portion 21 from the needle 110.

Since the needle bar 100 passes through the cross passing hole 211 provided in the presser foot arm 210 with a flow margin, minute shaking may occur in the pressing part 220 depending on the working situation, and the shaking of the pressing part 220 may adversely affect the stitch quality. In order to prevent such shaking, an elastic member may be provided between the presser foot arm 210 and the needle bar 100 so that the presser foot arm 210 and the needle bar 100 may be elastically pushed against each other in a predetermined direction.

The upper thread 20 to form the stitch on the surface of the sewing material 30 is lowered from the head frame 10 and passes through the needle hole 111. The upper thread 20 is usually drawn in from a front of the needle hole 111 and then discharged to a rear thereof. The downward extending portion 21 of the upper thread 20 that has passed through the needle hole 111 is lowered downward together with the needle 110 and passes through the needle guide hole 221 of the pressing part 220 to form the stitch on the sewing material 30, and is prepared in a state in which a certain tension is maintained through a separate tension holding device.

The sewing material 30, which is a sewing target, is pressurized and fixed by the pressing part 220 in the state of FIG. 1, the sewing material 30 is fixed to an embroidery frame in which the sewing material 30 is held horizontally, and the embroidery frame fluctuates in forward and backward and left and right directions within the horizontal plane by an X-Y driver.

Thereby, the sewing material 30 moves in the horizontal direction with respect to the needle 110, and the stitch position changes to form a desired pattern.

The excursion driver includes an excursion profile part 212 whose lateral protrusion height gradually changes along an elevating direction on the presser foot arm 210, and a contact action member 300 that contacts the excursion profile part 212 to apply an excursion acting force.

The excursion profile part 212 is formed in a downward extension section of the presser foot arm 210, and has a shape in which the lateral protrusion height gradually changes along the elevating direction. The contact action member 300 is in contact with the excursion profile part 212. The contact action member 300 is supported on the head frame 10 to contact the excursion profile part 212, and has a rolling contact part 310, such as a ball bearing or a roller bearing, provided on a surface that contacts the excursion profile part 212. As a result, when the presser foot arm 210 is elevated, the excursion acting force is applied to the presser foot arm 210 according to the shape of the excursion profile part 212 due to the action of the rolling contact part 310 contacting the excursion profile part 212. The excursion acting force excurses and moves the presser foot arm 210 and the pressing part 220 laterally. [29] The reaction elastic member 500 is disposed on an opposite side of the contact action member 300, having the presser foot arm 210 provided therebetween. The reaction elastic member 500 includes a spring 510 that elastically pushes the presser foot arm 210 in the direction of the contact action member 300, and a rolling contact part 511, such as a ball bearing or a roller bearing, that is provided at a distal end of the spring 510 to contact the presser foot arm 210.

FIG. 1 illustrates a state in which the needle 110 is lowered to be at the stitching position. At this time, the pressing part 220 is pressing the sewing material 30 downward, and is at the normal horizontal position where the needle 110 may pass through the needle guide hole 221. FIG. 2 illustrates the state in which the presser foot unit 200 and the needle 110 of FIG. 1 are lifted. At this time, the pressing part 220 is at the lifting release height position while being spaced apart from the sewing material 30, and is at the excursion horizontal spaced apart by a predetermined horizontal excursion amount (dS) as compared to the normal horizontal position.

In the state of FIG. 2, the excursion profile part 212 is subjected to the excursion acting force by the contact action member 300, and as a result, the pressing part 220 moves to the excursion horizontal position that excurses and moves by the predetermined horizontal excursion amount (dS) based on the normal horizontal position. The excursion movement state of the pressing part 220 is the same as the state indicated by a solid line in FIG. 3. The downward extending portion 21 of the upper thread 20 which is constrained by the needle guide hole 221 moves in the direction in which the pressing part 220 excurses and moves by the excursion movement of the pressing part 220, so the upper thread 20 is spaced apart from the needle 110 to prevent the interference that may occur between the leading end 112 of the needle 110 or the needle tip 113.

What is indicated by the dotted line in FIG. 3 indicates the state in which a downward extending portion 21′ of the upper thread 20 is in contact or interferes with the leading end 112 or the needle tip 113 of the needle 110 when the pressing part 220 does not move to the excursion horizontal position from the lifting release height position where the pressing part 220 does not press the sewing material 30. The interference state inevitably appears when the sewing material 30 moves relative to the front of the needle 110, and in this state, when the needle 110 is lowered to form a stitch, the upper thread 20 interferes with the leading end 112 of the needle 110 or the pointed needle tip 113 to be thread cutting or damaged. However, in the disclosure, since the pressing part 220 excurses and moves backward in advance and there is no interference between the upper thread 20 and the needle 110, the thread cutting or damage is prevented. The excursion horizontal position of the pressing part 220 illustrated in FIG. 3 is a position spaced apart by the horizontal excursion amount (dS) as compared to the case where the axial line of the needle guide hole 221 and the axial line of the needle 110 are disposed to match each other at the normal horizontal position.

Hereinafter, other embodiments of the disclosure will be described based on FIGS. 4 to 8. The same reference numerals are assigned to elements that are substantially the same as those of the first embodiment, and new reference numerals are indicated only for changed elements. Repetitive descriptions of the configurations that are common or can be shared with the first embodiment will be omitted.

FIGS. 4 and 5 each are diagrams illustrating the state where the pressing part 220 is at the normal horizontal position and the excursion horizontal position in the second embodiment. In the second embodiment, an excursion cam roller 1400 is employed to excurse and move the pressing part 220. That is, in order to achieve the same objects as in the first embodiment, the excursion cam roller 1400 is employed, and a rotation operation of the excursion cam roller 1400 is performed by a separate driver or interlocked with the needle bar 100. In addition, in the second embodiment, the presser foot unit 1200 is prepared as a presser foot arm 1210 having a flat shape that does not have the excursion profile part 212 as in the first embodiment and does not protrude laterally from the vertical direction.

The excursion cam roller 1400 may include a cam member 1410 that has a longer radial length in at least one direction of a cross section than the other direction, a rotation shaft 1420 that supports the cam member 1410, and a roller driver that rotatably drives the cam member 1410. At this time, the cam member 1410 is in contact with a side surface of the presser foot arm 1210.

The cam member 1410 may be supported so as to be freely rotatable with respect to the rotation shaft 1420. In this case, the roller driver may be constituted by an interlocking drive part that converts the elevating movement of the presser foot arm 1210 into the rotational movement of the cam member 1410, in which the interlocking drive part may be an interlocking friction part that increases a contact force between the cam member 1410 and the presser foot arm 1210, or interlocking gear parts that are provided on the side surface of the presser foot arm 1210 and the cam member 1410, respectively, to rotate while engaging with each other.

In addition, when the cam member 1410 is integrally rotated with the rotation shaft 1420, the roller driver may be constituted by an interlocking motor that rotates the rotation shaft 1420 in synchronization with the elevating movement of the needle bar 100.

As illustrated in FIG. 4, when the pressing part 220 is at the downward pressing height position, the excursion cam roller 1400 allows its short radial length of the cross section to contact with the side surface of the presser foot arm 1210 and to dispose the pressing part 220 at the normal horizontal position where the needle guide hole 221 and the needle 110 do not interfere with each other even if the needle 110 moves downward and passes through the sewing material 30, and as illustrated in FIG. 5, when the pressing part 220 is at the lifting release height position, the excursion cam roller 1400 allows its long radial length of the section to contact with the side surface of the presser foot arm 1210 and applies the excursion acting force to move the pressing part 220 to the excursion horizontal position moving by a predetermined horizontal excursion amount (dS) in the transverse direction with respect to the axial line of the needle. At this time, while the pressing part 220 excurses and moves horizontally, an inner side surface of the needle guide hole 221 is in contact with the downward extending portion 21 of the upper thread 20, and the upper thread 20 is spaced apart from the axial line of the needle 110 to prevent the upper thread 20 from interfering with the leading end 112 of the needle 110 or the pointed needle tip 113.

The first and second embodiments of the disclosure are understood as having the configuration that the presser foot units 200 and 1200 are synchronized with the elevating movement of the needle bar 100 to excurse and move the pressing part 220 using the elevating movement of the needle bar 100. Next, the embodiment of the form in which presser foot units 2200 and 3200 may have a separate elevating driver will be described.

FIGS. 6 and 7 each are diagrams illustrating a state in which a pressing part is at a normal horizontal position and an excursion horizontal position in a third embodiment. The presser foot unit 2200 according to the third embodiment is disposed independently without being directly interlocked with the needle bar 100, and has a separate driver (not illustrated) that drives the presser foot unit 2200 to move the presser foot unit 2200 up and down in synchronization with the elevating movement.

According to the third embodiment, the excursion driver includes an excursion profile part 2212 that is disposed on a presser foot arm 2210 and has an inclined surface extending downward, and a roller member 2600 that is in contact with the excursion profile part 2212 and applies the excursion acting force when the pressing part 220 is at the lifting release height position.

In this case, as illustrated, the presser foot arm 2210 may further include an elastic member in the form of a leaf spring 2510 that smoothly performs the excursion movement and the release of the excursion movement in some sections.

According to the third embodiment, the presser foot arm 2210 moves up and down in synchronization with the needle bar 100 by a separate driver, and in this process, when the presser foot arm 2210 is lowered as illustrated in FIG. 6 due to the action of the excursion profile part 2212 and the roller member 2600, the roller member 2600 does not apply the excursion acting force to the excursion profile part 2212 to move the pressing part 220 from the downward pressing height position to the normal horizontal position, and as illustrated in FIG. 7, when the presser foot arm 2210 is lifted, the roller member 2600 applies the excursion acting force to the excursion profile part 2212 to excurse and move the pressing part 220 from the lifting release height position to the excursion horizontal position, so the inner side surface of the needle guide hole 221 is in contact with the downward extending portion 21 of the upper thread 20 to separate the downward extending portion 21 from the needle 110.

FIG. 8 is a diagram illustrating a sewing machine according to a fourth embodiment. The fourth embodiment does not have a separate excursion driver, and the presser foot unit 3200 includes a presser foot arm 3210 that is inclinedly disposed along a driving axial line having a predetermined angle with the axial line of the needle 110 and a separate driver that drives the presser foot arm 3210 to move presser foot arm 3210 up and down along the driving axial line in synchronization with the elevating movement of the needle.

According to the fourth embodiment, the driver slidably drives the presser foot arm 3210 to move the presser foot arm 3210 up and down along the driving axial line, so the pressing part 220 is at the normal horizontal position where the axial line of the needle 110 and the axial line of the needle guide hole 221 match each other from the downward pressing height position, and is at the excursion horizontal position where the downward extending portion 21 of the upper thread 20 does not interfere with the needle 110 from the lifting release height position. At this time, the driving axial line corresponds to a moving axial line of the needle guide hole 221 at the normal horizontal position and the excursion horizontal position.

Hereinabove, as specifically describing the embodiments of the disclosure, according to the disclosure, the downward extending portion 21 of the upper thread 20 is spaced apart from the needle 110 when the needle 110 is lifted to prevent the interference between the upper thread 20 and the needle 110, thereby preventing the occurrence of the thread cutting or the deterioration in quality.

To this end, in moving the upper thread 20 forced by the pressing part 220 of the presser foot units 200, 1200, 2200, and 3200, the disclosure considers the possibility of all movement directions or movement paths in which the upper thread 20 can be prevented from interfering with the needle 110. For example, in the most ideal cases, the spaced direction of the upper thread 20 is preferably made within a plane including the axial line of the needle hole 111 and the axial line of the needle 110. However, even if the movement direction of the upper thread 20 slightly deviates from the plane including the axial line of the needle hole 111 and the axial line of the needle 110, there is no problem in achieving the object of the disclosure. However, it is recommended that the downward extending portion of the upper thread comes into long contact with the surface of the needle not to be wound.

The upper thread 20 generally moves in a spaced direction along a straight path. However, in some cases, the upper thread 20 may move along a curved path or an arc-shaped path. For example, it may be considered that the needle guide hole 221 of the pressing part 220 pivots about an arbitrary pivot center spaced therefrom, and reciprocates between the normal horizontal position and the excursion horizontal position.

In addition, in the embodiments, the presser foot arms 210, 1210, 2210, and 3210 are disposed at the rear from which the upper thread 20 is discharged from the needle hole 111 and moves to the rear of the needle 110 by the excursion acting force, and excurses and separates the downward extending portion 21 of the upper thread 20 from the needle 110. However, the position of the presser foot arm is not limited thereto, and may be disposed on the left or right side or in front of the needle 110, and the direction in which the presser foot arm is applied with the excursion acting force is also not limited to the illustrated matter.

In the disclosure, the pressing part 220 is disposed at the normal horizontal position by releasing the excursion acting force at the downward pressing height position, and moves to the excursion horizontal position by being applied with the excursion acting force at the lifting release height position. However, on the contrary, the pressing part 220 may be applied with the excursion acting force at the downward pressing height position to be disposed at the normal horizontal position, and may move to the excursion horizontal position by releasing the excursion acting force at the lifting release height position. In addition, the presser foot arm is always supported while receiving the excursion acting force, and when the pressing part 220 is at the lifting release height position, the excursion acting force is released so that the pressing part 220 moves to the excursion horizontal position, or when the pressing part 220 is at the downward pressing height position, the excursion acting force is released so that the pressing part may move to the normal horizontal position.

In adddition, the excursion profile part 212 has a shape which protrudes laterally in the direction of the contact action member 300 so as to be applied with the excursion acting force from the contact action member 300 when the pressing part 220 is at the lifting release height position, but may have various shapes depending on the direction of the excursion acting force and the position of the contact action member 300. In addition, the lateral protrusion height of the excursion profile part 212 smoothly changes linearly, and thus the presser foot arm 210 moves up and down to enable the pressing part 220 to be linearly perform an excurse movement and return movement between the normal horizontal position and the excursed horizontal position, but it is possible to intermittently change between the normal horizontal position and the excursion horizontal position during the lifting by adjusting the change of the lateral protrusion height.

The needle guide hole 221 may have various shapes, and may be prepared to have an opened shape in which some sections are opened. However, the downward extending portion 21 of the upper thread 20 needs to be spaced apart from the needle 110 by contacting the needle guide hole with the downward extending portion 21 of the upper thread 20.

In the illustrated embodiment, the reaction elastic member 500 is provided with a spring 510, but the acting force of the spring 510 may be replaced by the intrinsic elastic force of the presser foot arm 210 itself, and the reaction elastic member 500 may also be replaced with a spring having other shapes such as a leaf spring or a coil spring. 

1. A sewing machine, comprising: a head frame; a needle bar configured to be supported on the head frame to be movable up and down; a needle configured to have a needle hole that penetrates in a transverse direction with respect to an axial line and has an upper thread inserted thereinto and be coupled to a lower end of the needle bar to move up and down between a lowered stitching position and a lifted needle position; and a presser foot unit configured to: have a pressing part that is provided with a needle guide hole through which the needle passes, and moves up and down between a downward pressing height position where the pressing part presses a sewing material and a lifting release height position where the pressing part is lifted and spaced apart from the sewing material, and a pressing foot arm that supports the pressing part, and dispose the pressing part at a normal horizontal position so that the needle passes through the needle guide hole when the pressing part is at the downward pressing height position, and horizontally move the pressing part from the normal horizontal position to an excursion horizontal position spaced by a predetermined horizontal excursion amount so that the upper thread passing through the needle hole does not interfere with a leading end of the needle when the pressing part is at the lifting release height position.
 2. The sewing machine of claim 1, wherein the presser foot arm supports the pressing part to enable the pressing part to perform an excursion movement and a return movement between the normal horizontal position and the excursion horizontal position, and further including an excursion driver configured to apply an excursion acting force to the presser foot arm to cause the pressing part to perform at least one of the excursion movement and the return movement.
 3. The sewing machine of claim 2, wherein the excursion driver includes an excursion profile part whose lateral protrusion height gradually changes along an elevating direction on the presser foot arm , and a contact action member that contacts the excursion profile part to apply the excursion acting force.
 4. The sewing machine of claim 3, wherein the contact action member has a rolling contact part.
 5. The sewing machine of claim 2, wherein the excursion driver includes an excursion cam roller that rotates in contact with side surface of the presser foot arm and applies the excursion acting force to the presser foot arm, and a roller driver that rotatably drives the excursion cam roller by interlocking with an elevating movement of the presser foot arm.
 6. The sewing machine of claim 2, further comprising: a reaction elastic member configured to apply an elastic force to the presser foot arm in a direction opposite to the excursion acting force. 